The present invention pertains to an inkjet printer comprising a print head mounted on a carriage and an off-carriage ink reservoir, the carriage being arranged for moving the print head relative to a receiving medium. The printer comprises a hose for connecting the print head to the reservoir to enable the supply of ink from the reservoir to the print head, the hose having a multi-layered wall. The present invention also relates to the use of the hose in the inkjet printer.
The printer is known from U.S. Pat. No. 5,988,801. The known printer includes a medium transporting system for transporting the receiving medium along a medium path to a print area and a scanning carriage for holding the print head. The carriage can be scanned along a scanning axis transverse to the media path at the print area. The printer includes a fixed ink supply station including an ink reservoir. In order to connect the movable print head to the reservoir, the printer is provided with a fluid conduit for the flow of ink, the conduit comprising a flexible hose having a multi-layered wall and routed such that a flexible loop is formed therein. The multi-layered wall provides for a sufficient barrier to water vapor transmission and oxygen permeability. This kind of separate fixed ink supply arrangement is typical for large format printers, e.g., for plotting engineering drawings and printing color posters. For these applications there is a requirement for the use of much larger volumes of ink than the volumes that can be contained within the print heads themselves. Therefore, separate ink reservoir systems have been developed which provide an external stationary ink supply that is connected to the scanning print head via a hose. The external ink reservoir is known for example as “off-axis”, “off-board”, or “off-carriage”. In the known printer, typical problems with these off-axis ink reservoirs, such as mechanical damage of the hose due to an induced kink, vapor losses from the hose, air diffusion into the hose etc. have been resolved adequately by providing a flexible multi-layered wall, each layer having it's own dedicated task to avoid the known problems. This has been outlined in great detail in the above identified U.S. patent, starting in column 3, line 64 end ending in column 7, line 53. However, the known inkjet printer has an important disadvantage. The durability of the hose is relatively poor. After a few months of operation of a typical large format printer, the air and vapor tightness of the hose can decrease to an inadequate level. It is also known that the layers can separate which may cause mechanical damage to the hose, resulting in inadequate water vapor and air tightness. Accordingly, the problems known before, such as the change of ink properties, degrading print quality, print head starvation etc. may again arise. Replacement of the bad hose often requires replacement of the complete tubing system, which is relatively expensive.